Don’t flush your goldfish. Better yet do not turn any pet out into the wild. If you cannot take care of it give it to someone that can or have it put down. Turning domesticated or exotic pets out into the wild only causes problems within the local ecosystem. If the goldfish link does not convince you of this I recommend you do some research into the damage caused by pythons in the Everglades or the devastation of Hawaii’s honey creepers by non-native predators such cats and snakes.